JPH0410206A - Bonded magnetic head - Google Patents

Abstract

PURPOSE:To improve an S/N between a color and a luminance signal by composing a ferrite monocrystal and ferrite polycrystal as prescribed. CONSTITUTION:The composition of the ferrite monocrystal and the ferrite polycrystal is regulated to Fe2O3(52-56mol%), MnO(25-30mol%) and ZnO(15-21mol%) for the bonded magnetic head. Then, in a pair of cores having a sliding surface (112) with a magnetic tape, gap abutting surface (110) and magnetic path forming surface (111) adjacent to the sliding surface and the abutting surface, two crystal axes [110] having the angle of 60 deg. each other rare composed of front magnetic gap parts in a crystal azimuth drawing arrow patterns in a direction where the patterns are mutually approached toward the sliding surface. On the other hand, for this bonded magnetic head, the particle diameter of the polycrystal ferrite is regulated less than 15mum. Thus, without lowering the reproducing output of a head tape system, sliding noise is sharply reduced and the C/N of the head tape system is sharply improved as well.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a junction type magnetic head, and particularly to a magnetic head for video recording of a VTR.

(Conventional technology vfX) In order to meet the needs for higher image quality, household VTRs that use magnetic tapes with high coercive force and high magnetic flux density have a recording wavelength of about 08 μm, which is about 40% shorter than before. Therefore, the recording/reproducing sensitivity of the tape head transmission system is also required to have good characteristics on the higher frequency side. In particular, the characteristics around 7 to 9HH7 affect the resolution of the VTR playback screen.

FIG. 6 is an explanatory diagram for explaining the crystal orientation of a conventional ferrite single crystal magnetic head (A), in which a pair of core halves 10a
, 10b is a HnZn ferrite single crystal, whose composition is Fe203 (52-56 mol%),
MnO (25-30 gao1%), ZnO
(15-21a+o1%), and the sliding contact surface 11a111b with the magnetic tape (not shown) is (112}, the gap abutting surfaces 12a, 12b are (111), and the sliding contact surfaces 11a, 11b and the gap abutting surfaces 12a, 12
The magnetic path forming surfaces 13a and 13b adjacent to b are (11), and the crystal axes of the pair of core halves 10a and 10b are [
1101 in the direction facing the sliding surfaces 11a and 11b, and
The crystal orientation is such that an arrow-head pattern approaches each other.

FIG. 7 is a spectrum diagram of a reproduced output signal measured from the magnetic head (A) having the above configuration.

In the same figure, the magnetic head (A) has particularly narrow track width (e.g. 30μ
m or less), the C/N ratio, which indicates the signal/11 tone ratio of the tape head system, is poor and the image quality of the VTR in long-time mode is poor.
/N and resolution are not satisfactory, and improvements are being considered.

Figure 8 shows the Hn of Figure 6 as a solution to the above problem.
This is a magnetic head (B) in which the configuration of the crystal plane of the magnetic head (A>) using a Zn ferrite single crystal is changed.

In the figure, the vibrating surfaces 11a and 11b with the magnetic tape are (112), the gap abutting surfaces 12a and 12b are (110}, and the magnetic path is formed adjacent to the sliding surfaces 11a and 11b and the gap abutting surfaces 12a and 12b. Surface 13a
, 13b as (111), a pair of core half-vacations 10a,
Inside the magnetic head, the two crystal axes [110] of each of 10b, which form an angle of 60° with each other, are oriented in a direction toward the sliding surfaces 11a and 11b, drawing an arrow-head pattern approaching each other. If the angle that one crystal axis [110] makes with the gap abutting surfaces 12a and 12b is θ, then the other crystal axis [110] of the two crystal axes [110] forming an angle of 60° with each other is the gap abutting surface 12a, 12b. surface 12a,
The angle α formed with 12b is α=θ+60° (60°≦α≦9
0°).

FIG. 9 shows the reproduction output of 78H2 measured using α=θ+606 as a parameter.

In the same figure, α=60° and α=90°, that is, the core half-closed surface configuration is such that the gap abutting surfaces 12a and 12b are (1
10}, a magnetic head in which the sliding surfaces 11a and 11b are (112), and the gap abutting surfaces 12a and 12b are (1
12}, IW The magnetic head whose moving surfaces 11a and 11b are (11) is excellent in reproduction output.

FIG. 10 is a spectrum diagram of the reproduced output signal measured from the magnetic head (B).

Comparing Figures 7 and 10, we find that the magnetic head (B)
Since the noise is caused by head opening noise, the noise is increased by approximately 2 to 5 dB at all frequencies compared to the magnetic head (A). Therefore, the C/N of the luminance signal (6.58 Hz) is degraded by about 3 db compared to the magnetic head (A).

FIG. 11 is a diagram showing the relationship between the reproduction output and frequency of the magnetic heads (A}, (B).

In the same figure, the reproduction output of the magnetic head (B) is improved in the high frequency range compared to the magnetic head (A), but as mentioned above, the sliding noise also increases, so the C
/N characteristics are approximately adb in the luminance signal (5 to 7 Hz) band.
Also, the quality of the VTR's playback image cannot be improved.

Regarding the reduction of these vibrational noises, various studies have been carried out, especially on improving the sliding noise peculiar to ferrite A crystal heads. 48891,
Japanese Patent Publications No. 60-26076, No. 61-3313, No. 43-12098, No. 47-10193, etc. are known.

These slide contact surfaces 11a and 11b with the magnetic tape are Hn
This is a composite head that uses Zn ferrite single crystal and Hn7n ferrite polycrystal for the part that makes up the rear magnetic circuit, and takes advantage of the polycrystal's property of randomly generating magnetostriction to cancel out ambient noise. There is.

Methods for compositing (joining) this HnZn ferrite single crystal and HnZn ferrite polycrystal include (1) direct joining by solid-phase reaction between the two, (2) direct joining of the two, and a mutual diffusion layer formed by heat compression bonding. There are two methods: (3) a method of heat-pressing the two through glass.

Composite magnetic heads made using the above three methods have reduced sliding noise by approximately 2 to 3 db compared to Hn2n ferrite single crystal heads with the same composition, achieving the initial objective, but the reproduction output value The S/
No improvement is observed when comparing the N ratio.

(Problems to be Solved by the Invention) As mentioned above, when the conventional magnetic heads (A}, (B) made of ferrite single crystals increase the reproduction output in the high frequency range, the sliding noise also increases accordingly. As a result, S
This had the disadvantage of lowering /N.

In addition, the conventional HnZn ferrite single crystal and HnZn
Although the ferrite polycrystal composite magnetic head reduces sliding noise, it has the disadvantage that the reproduction output sensitivity also decreases approximately in proportion to the sliding noise.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and includes: 1) a front magnetic gap part of a magnetic tape sliding part made of a ferrite single crystal and a ferrite polycrystal; In a junction type magnetic head consisting of a core and a magnetic path forming section,
The compositions of the ferrite A crystal and the ferrite polycrystal are Fe203 (52-56101%), MnO (25-56101%),
30 mol%}, 1nO (15 to 211101%), and the sliding surface with the magnetic tape is (112},
Two crystal axes at an angle of 60° to each other of a pair of cores each having a gap abutting surface as (110} and a magnetic path forming surface adjacent to the sliding contact surface and the abutting surface as (111) 110] is characterized in that the front magnetic gap portion is oriented in a direction facing the sliding surface and in a crystal orientation drawing an arrow-head pattern approaching each other; and 2) the polycrystalline magnetic head. It is an object of the present invention to provide a junction type magnetic head according to claim 1, wherein the grain size of the ferrite is defined to be 15 μm or less.

(Example) The present invention uses Fe203 (53 to 56
mol%), MnO (25-30 mol%}
, monocrystalline and polycrystalline ferrite materials in the range of lnO (16 to 20 mol%) with a difference in thermal expansion coefficient of ±10%, their joint surfaces are polished to a mirror surface, and then For example, heat and pressure bonding is performed under the following bonding conditions.

In a nitrogen atmosphere (0,517m+n) (1) From room temperature to 650°C at a heating rate of 200°C/H (2) From 650°C to 1050°C at a heating rate of 150°C/H (3) At 1050°C IH and pressurization to 100 ko/
-, (4) 100℃/H from 1050℃ to room temperature
Lower the speed at the lower speed.

Using the bonded ferrite produced under such bonding conditions, a bonded magnetic head is manufactured by a well-known head manufacturing method.

FIG. 1 is an explanatory diagram of a magnetic head (C) of the present invention manufactured by the above-mentioned manufacturing method.

In the figure, 20a and 20b are HnZn ferrite single crystals, 21a and 21b are HnZn ferrite polycrystals, and 2
2 is a magnetic gear made of Si02 glass, 23a, 2
3b is the mold glass in the track width regulating groove, 24 is the HnZn ferrite single crystal 20a, 20b and HnZn.
This is the junction boundary between the ferrite polycrystals 21a and 21b, and the junction between the front magnetic gap section and the magnetic path forming section of the core.

In the magnetic head (C) constructed as described above, the portion constituting the front magnetic gap of the tape sliding portion is made of Hnln ferrite single crystals 20a and 20b, and the magnetic path forming portion of the core is made of HnZ.
Consisting of two n-ferrite polycrystals a and 21b, the Hn
The sliding surfaces 25a, 25b of the ln ferrite single crystals 20a, 20b with the magnetic tape are (112), and the gap abutting surfaces 26a, 26b are (110) 1.1 m sliding surface 2
The magnetic path forming surfaces 27a and 27b adjacent to the gap abutting surfaces 26a and 26b are set to (111), and the two crystal axes [1101 are in the direction facing the sliding surface, and
The crystal orientation is such that an arrow-head pattern approaches each other.

The angle that one of the two crystal axes [110] of this magnetic head (C) makes with the gap abutting surfaces 26a and 26b is θ,
The angle formed with the other gap abutting surfaces 26a and 26b is α, and among those satisfying α−θ160°, θ−3
The angle is 0°.

Figure 2 compares the reproduction output characteristics of the bonded ferrite head (C) of the present invention and the all-single-crystal head (B), which has the same composition as the bonded ferrite head (C). , bonded ferrite head (C) of the present invention
Almost the same reproduction output as the single crystal ferrite head (B) is obtained.

FIG. 3 is a spectrum diagram of a reproduced output signal measured from the bonded ferrite head (C) of the present invention, and the signal is 6.58H2.

Comparing the spectrum diagram of the magnetic head (B) in the same figure with the magnetic head (A> in Figure 9 mentioned above), even though the signal output at 6.5MHz is the same, the noise difference due to sliding noise is greater than that of the entire frequency. The C/N ratio of the bonded ferrite head of the present invention is 3 to 4 db higher than the magnetic head (B), and 1 to 2 db higher than the current magnetic head (A).
An improvement of 2db is observed.

FIG. 4 is a diagram showing the relationship between the crystal grain size of the polycrystalline material of the bonded ferrite head (C) of the present invention and the reproduction output. 5
Low frequency (f=0.
5HH7) and a high frequency (f=78H2).

From the figure, it can be seen that the reproduction output at both low and high frequencies is excellent when the crystal grain size of the polycrystalline material is 15 μm or less.

Figure 5 is a diagram showing the relationship between the crystal grain size of the polycrystalline material of the bonded ferrite head (C) of the present invention and the sliding noise. In order to increase the ratio of noise to noise, it is desirable that the grain size of the polycrystalline materials 21a and 21b of the bonded ferrite head (C) be 15 μm or less, as shown in FIGS. 3 and 4.

(Effects of the Invention) As described above, 1) A junction type magnetic head consisting of a front magnetic gap part of a magnetic tape sliding part made of a ferrite single crystal and a magnetic path forming surface of a core made of a ferrite polycrystal. In,
The composition of the ferrite single crystal and the ferrite polycrystal is Fe203 (52 to 56 mol%), MnO (25
~30 mol%), ZnO (15~21 mol%
), and the sliding surface with the magnetic tape is (112
}, the gap abutting surface is (110}, and the magnetic path forming surface adjacent to the sliding contact surface and the abutting surface is (111).
The two crystal axes [1101] of each of the pair of cores having an angle of 60° with respect to each other face the sliding surface and approach each other in an arrow-head pattern. and 2) the junction type magnetic head according to claim 1, wherein the grain size of the polycrystalline ferrite is defined to be 15 μm or less. , the sliding noise can be significantly reduced without reducing the playback output of the head/tape system, and the C/N of the head/tape system can also be greatly improved. Therefore, color S/N,
The S/N ratio of the luminance signal is also improved, making it possible to provide a magnetic head that can provide image quality with improved color characteristics and resolution.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the junction type magnetic head (C) of the present invention, Figure 2 is a reproduction output characteristic diagram of the junction type magnetic head (C) and the single crystal magnetic head (B) of the invention, and Figure 3 is A spectrum diagram of a reproduced output signal measured from the junction type magnetic head (C) of the present invention, FIG. Fig. 5 is a diagram of the relationship between the crystal grain size of the polycrystalline material and sliding noise of the junction type magnetic head (C) of the present invention, and Fig. 6 explains the crystal orientation of the conventional ferrite single crystal magnetic head (A). FIG. 7 is a spectrum diagram of the reproduced output signal measured by the magnetic head (A), FIG. 8 is an explanatory diagram of the magnetic head (B) using Hn2n ferrite single crystal, and FIG. B) 7
The reproduction output diagram for 8H2, Figure 10 shows the magnetic head (B
), and FIG. 11 is a diagram showing the relationship between the reproduction output and frequency of the magnetic herad (A}, (B). 20a, 20b-Hn2rl 7 Elite single crystal,
21a, 21'0-HnZn7x light polycrystal,
22...5102 Magnetic gap due to glass film, 23
a, 23b...Mold glass in the track width regulating groove, 24-...HnZn ferrite single crystal 20a, 20b
and the junction boundary between Hn7n ferrite polycrystals 21a and 21b.

Claims (1)

[Scope of Claims] 1) A junction type magnetic head consisting of a front magnetic gap part of a magnetic tape sliding part made of a ferrite single crystal and a magnetic path forming part of a core made of a ferrite polycrystal,
The composition of the ferrite single crystal and the ferrite polycrystal is Fe_2O_3 (52 to 56 mol%), MnO (25
~30 mol%), ZnO (15 to 21 mol%), the sliding surface with the magnetic tape is {112}, the gap abutting surface is {110}, and the magnetic tape adjacent to the sliding surface and the abutting surface is An arrow-head pattern in which the two crystal axes [110] of each of the pair of cores having a {111} track forming surface at an angle of 60° to each other face the sliding surface and approach each other. A junction type magnetic head characterized in that the front magnetic gap portion has a crystal orientation that depicts. 2) The junction type magnetic head according to claim 1, wherein the grain size of the polycrystalline ferrite is defined to be 15 μm or less.